Annals of Botany

Position and picloram pull together  in peach palm programme

Many of our readers will be unfamiliar with peach  palm (Bactris gasipaes). It is native to Central America and  northern South America and was widely cultivated by indigenous peoples  before the arrival of European settlers, who ignored it, preferring crops  with which they were more familiar. However, peach palm is coming back  into favour and is regarded as having great potential, although it is  listed by the International Plant Genetic Resources Institute (www.biodiversity.org) as a neglected crop. Nevertheless, breeding programmes are under  way and, as aid to those programmes, there is also active research on  tissue culture and micropropagation, as typified by the work of  Steinmacher et al. (Florianopólis and Manaus, Brazil,  pp. 699–709). They used zygotic embryos as  starting material for establishing callus cultures. A key part of their  technique is the use of very thin (0·7–1·0 mm)  explants. The main factors in the establishment of callus were the position  from which the explant came (the shoot apex and the immediately sub-apical  zone were best) and the presence of the auxin analogue, picloram at concentrations of 150–600 µm. Embryogenic potential  was at its highest (43 %) in calli from apical explants cultured  with 300 µm picloram. A good proportion of these  embryogenic calli actually went on to form functional somatic embryos  from which plantlets were established. The use of amplified fragment length  polymorphism (AFLP) enabled the authors to compare the genomes of the  cloned plantlets with their ‘mother’ plants, thus giving a  possible indication of somaclonal variation. Most (92 %)  of the plantlets were true to type, at least at the level of detection  afforded by AFLP, whilst 8 % showed gain or loss of  amplified fragments. It is obvious then that this thin-cell-layer technique  is useful in micropropagation of peach palm, even though the authors  state, rather modestly, that further optimization is needed.